RVing cross country (4 times, so far) I (we) much prefer our overnights at a cg. Yeah...costs a few bucks, but we feel much better...and safer. Mostly KOAs but use non-KOAs when zthe occasion arises. Never a problem.
Only once after a totally exhausting day...did we elect to stay overnight at a Wal-Mart...in a town called Seminole, Texas. We did go in the store, found the manager and asked for permission to stay....no problem. And...we bought some stuff. Didn't really need anything...but kinda like a "thank you".
For whatever reason, we were not comfortable, slept fitfully and left around 4:30AM to continue our travel. Nothing happened...perhaps our anxiety was unfounded, but there it was.
We hve a Wal-Mart not 5 miles from our house. The nearest cg is at least 40 miles away...but no overnight parking. Not from Wal-Mart, but from the township.
It's always a few that screw things up for the many.